I am a dumbass that couldn't take the advise you are now getting. I bought one anyhow.The model I have clamps right on the flatop and has a ar type adj sight built into the rear of the thing. It is slow to aquire a sight picture as you are looking thru the standard apeture. I tried useing it for a carbine class and as soon as I lost a perfect cheek weld I lost the sight picture. So I took apart the rear iron sight goodies to use it as a plain red dot unit (and gave up any possible use of back up iron sight features).It has a good bright dot and a good brightness control. Battery life seems very good,but I only use it for fun and games so I guess I have not tested it that well. It seems fairly durable but then again I have only played games with it.
As said the adjustment is very coarse and impercise. There are two adjustment screws and each have a lock screw. The adjustment screw is very coarse and next to imposible to hold solid as you tighten the lock screw. You will be chaseing your zero all over the map trying to get it set where you want it. The sight itself is a sloppy fit on the standard flatop rail on my bushmaster and stag uppers and as I try to count notches and hold one way or another against a notch it still doesn't find the same zero when dismounted and remounted.
Turns out the only game I use it for is indoor rimfire plate matches (short 12yd match). With the sight taken apart as I have said this is fast and easy to accuire a sight picture.
I originally bought this sight to use at a local carbine course where the targets are steel plates 6"-10" at 50 to 100 yards and clay pidgeons at 10 to 25 yards and I just could not get a satisfactory zero.
Not like this unit is a great deal $wise- stay away!